Oven for controlling heating and curing of resinous insulating material

ABSTRACT

An oven for heating and curing a powder of heat hardenable resinous material that has been applied to the portions of coil windings in a slot of a magnetic core as well as to the coil end turns including at least two heating panels disposed at spaced distances from the coated coil windings, the panels having a plurality of infrared radiant energy sources directed towards the coil windings, the panels being movable toward and away from the position of the coil windings, and control means associated with the panels for measuring the temperature of the resinous coating on the coil windings during the heating and curing operation, which means are operatively connected to the circuit of the infrared heat sources for turning the source on and off at prescribed intervals.

United States atent [1 1 [111 3,732,066 Kipple et al. 1 May 8, 1973 [541 OVEN FOR CONTROLLING HEATING 3,159,387 l2/l964 Campbell, Jr. et al ..263/40 R AND CURING 0 RESINOUS 3,119,606 l/l964 Suydam et al. ..263/40 R INSULATING MATERIAL Primary Examinerlohn J. Camby [75] Inventors: Harry P. Kipple, Pittsburgh, Pa.; An0mey p" Shapoe et 1 Virgil J. Cozzarin, Clarence, N.Y.; Francis C. Kapperman, deceased, [57] ABSTRACT late of Eggertsvlue F An oven for heating and curing a powder of heat Dorothy M. Kapperman, admmrsh d bl t 1 m t h b d t tramx ar ena e resinous ma e ria a as een app 1e 0 the portlons of COll WlIldll'lgS In a slot of a magnetic [73] Assignee: Westinghouse Electric Corporation core as well as to the coil end turns including at least Pittsburgh, Pa. two heating panels disposed at spaced distances from the coated coil windin s, the anels havin a luralit [22] Flled: 1970 of infrared radiant en ergy s urces direct ed iowardz [21] App1.No.: 89,797 the coil windings, the panels being movable toward and away from the position of the coil windings, and [52] US Cl ..432/49,432/32,432/50. control means associated with the panels for measur 432/225 432/227 ing the temperature of the resinous coating on the coil [51] Int. Cl ..F27b 3/02 windings during the heating and curing operation [58] Field of Search ..263/2, 4, 5, 40, which means are operative), connected to the circuit 263/43 of the infrared heat sources for turning the source on and off at prescribed intervals. [56] References Cited 6 Claims, 5 Drawing Figures UNITED STATES PATENTS 2,342,045 2/1944 Fuller ..263/S R X -60 so 12 1 2:i 30

l I I J 54 5O ,le -l6A #26 70 a I l m A 72 42 e 20 PATENTED HAY 8 197a SHEET 1 OF 3 PATENTEDHAY'BIW 3,732,066

SHEET 2 OF 3 EXHAUST PATENTED MY- 81975 SHEET 3 BF 3 FIG.5

FIG.4

OVEN FOR. CONTROLLING HEATING AND CURING OF RESINOUS INSULATING MATERIAL CROSS REFERENCE TO RELATED APPLICATION This invention is related to application Ser. No. 89,800 filed Nov. 16, 1970 concurrently herewith, now US. Pat. No. 3,683,154.

BACKGROUND OF THE INVENTION D 1. Field of the Invention This invention relates to an oven for fusing and curing particles of resinous materials that have been applied to coil windings within a slot of magnetic core such as a motor stator, as well as to the coil end windings.

2. Description of the Prior Art Rotating electrical apparatus such as motors and generators, employ insulated coils comprising central core portions and end turn portions. The preparation of coils, windings, or conductors for insertion into slots of magnetizable cores by prior methods has involved the time. consuming and costly process of applying insulation tape, wrappers, and slot cell liners to the coil portions, such as disclosed in US. Pat. No. 3,054,770. The process, was particularlyinvolved where it was employed in the repair of coils for motors and generators.

. A method that would eliminate or reduce the amount of taping and wrapping required for all types of rewound rotating apparatus would be desirable. In addition to reducing the labor required in the rewinding f the coil windings, a reduction of subsequent treatment cycles has been sought. More particularly, in the area of form wound coils for stators, rotors, and armatures with, for example, direct current fields, and rotating fields, the methods have remained the same, i.e., mostly the hand taping of the assembled conductors, varnish treatment and approximately 12 hours baking cycles. The foregoing problems are of greater moment where repair shops for processing such apparatus are involved. Repair shops handle apparatus of various sizes and are therefore necessarily faced with a wide variety of non-standardized coils of different shapes and sizes and needing different varnishes requiring different applying and curing procedures. For example,

repair shops must be prepared to handle components of rotatable apparatus varying in diameter from 4 inches to 6 feet or more. In such circumstances the methods employed must be adapted to a maximum output at a minimum cost. I

The use of heat hardenable resinous materials as insulation for coil windings both within the magnetic core slot as well as the coil end turns has been considered as a method of obviating the prior method of taping and wrapping as disclosed in said patent. A deterrant factor to the use of resinous materials, however, has been the lack of a suitable means for rapidly heating and fully curing the materials after they have been applied to the windings. That is particularly true where the insulation material is applicable as particles of powdered resinous material.

Associated with the foregoing has been a problem of controlling the source of heat and adapting it to the curing time of the particular resinous material involved.

SUMMARY OF THE INVENTION In accordance with this invention is has been found that the foregoing problems may be overcome by providing an oven for heating and curing a coating of heat hardenable resinous materials in place on coil windings in a slot of a magnetic core which oven comprises support means for mounting the magnetic core in place, a heating panel on at least one side of the support means, the panel having a source of infrared energy for heating the resinous coating on the coil windings, and means for measuring the temperature of the resinous coating and for controlling the output of the source of infrared energy, whereby the powdered particles of resinous material are fused together and cured as a continuous insulating coating on the coil windings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of the oven taken on the line I-I of FIG. 2;

FIG. 2 is an end elevational view of the oven;

FIG. 3 is an enlarged vertical sectional view taken on the lineIII--III of FIG. 1;

. FIG. 4 is an enlarged view taken on the line IVIV of FIG. 1; and

FIG. 5 is a vertical sectional view taken on the line V- V of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, an oven is generally indicated at 10. It includes a frame 12, a pair of heating panels 14 and 16, temperature control means or radiation thermometers l8 and 20 and a pair of sliding doors 22 and 24 on opposite sides of the oven.

The frame 12 includes four similar legs 26 (two of which are shown in FIG. 1), a pair of horizontal beams 28 (one of which is shown in FIG. 1), and a pair of inner connecting cross members 30 extending between opposite corresponding ends of the beam 28. At the lower end of two of the legs 26 wheels 32 are mounted and at the lower end of another pair of the legs 26. A grooved wheel 34 is mounted and disposed in engagement with a track 36. The wheels 32 and 34 enable movement of the oven 10 to facilitate placement of a rotor 38 on a pedestal 40, such as, by an overhead crane after which the oven 10 may be rolled into place over and around the rotor 38 in order to cure layers 42 of heat curable resin on the end coils 44 of the rotor.

As shown in FIG. 1, all other portions of the oven 10 including the heating panels 14, the thermometers 18 and the sliding doors 22 and 24 are suspended from the top of the frame 12 and particularly the beams 28. The heating panel 14 includes a plurality of horizontally disposed rdiation heat lamps 46. The lamps 46 in the panel I4 extend between a similar pair of vertically disposed arms 48. Likewise, the heat lamps 46 in the panel 16 are supported between a pair of spaced vertical arms 50. The upper ends of the arms 48 are attached to slide bars 52 in the upper ends of the arms 50 are attached to similar slide bars 54.

As shown more particularly in FIG. 3, the upper edge portion of the slide bar 52 extends into an inverted C- shaped channel track 56 which is attached to the underside and is coextensive with the beam 28. Pairs of rollers 58 are attached to the upper edge portions of each plate 52 for rolling engagement with the interior of the channel track 56 as shown in FIG. 3. As was indic'ated above, each end of the panel 14 is suspended from similar slide bars 52 which are in rolling engagement with similar channel tracks 56 that are attached to both horizontal beams 28. The panel 16 is similarly suspended from the pair of slide bars 54 the upper edges of which are also provided with rollers 60 that engage the same track 56 as the rollers 58 on the panel 14. Thus, the panels 14 and 16 are movable along the tracks 56 toward and away from the workpiece or rotor 38 in order to obtain the proper spacing from the heat lamps 46 during the curing.

As shown in FIG. 1 and more particularly in FIG. 3, both pairs of doors 22 and 24 are suspended from spaced pairs of rollers 62 which are rollingly mounted in a channel track 64 adjacent to the track 56 and attached to the undersurface of the beam 28, whereby both pairs of doors 22 and 24 may be opened for setting up the operation prior to turning on the heat lamps 46. When the lamps 46 are on for curing, the layer 42 of resin on the end coils 44 the doors 22 and 24 are closed as shown in the solid line position thereof in FIG. 1. During the curing operation, the chamber surrounding the stator 38 becomes heated and a pair of heat barrier walls 66 are provided between opposite pairs of slide bars 52 and 54. In addition, a sealing 68 is provided between the top side of the spaced beams 28 which sealing extends throughout the distance of complete spacing of the walls 68 when the beams 14 and 16 are opened to their widest distance as indicated by the broken line positions 14A and 16A.

The heat lamps 46 are preferably infrared lamps having a pair of quartz tubular heating elements 70 for each lamp. Each lamp 46 also includes a three-sided reflector 72 which reflects the heat generated by the heating element 70 from the elements and toward the workpiece or stator 38. Thus, each lamp 46 provides radiant energy heating the source of which heat for each lamp is a coiled tungsten filament (not shown) which extends from one end to the other of each quartz tube heating element 70. The filament operating temperature is approximately 4000F. During the heating and curing period all or a portion of the lamps 46 may be used, depending upon the size of the rotor 38.

Ordinarily, during their operation, the lamps 46 are controlled to turn them on and off during a selected percentage of their total operation time in order to gradually heat the layer 42 of resin to the desired fusion and curing temperature such as about 380F. After the layer 42 of resin is brought to that temperature, or any other temperature depending upon the type of resin used, the temperature of the resin is closely controlled in order to obtain optimum curing in a minimum of time without burning the resin. For that resin, the lamps 46 may be on during greater or lesser percentages of their complete operation time as dictated by the characteristics and curing time for the particular resin used.

Control means including the radiation thermometers l8 and 20 are provided for measuring the temperature of the layers 42 of resin during the preliminary heating as well as the final curing phases. One type of radiation thermometer that is useful for that purpose is the IRCON 700 series radiation thermometer provided by IRCON Inc. of Chicago, Ill. for measuring temperatures from 100 to 4000F without contact. The radiation thermometers 18 and 20 are dependent upon the intensity of radiation of the temperature of the layer 42 of resin. Inasmuch as all heated bodies emit infrared radiation, the thermometers 18 and 20, being provided with an optical system for collecting the radiation and focusing it on a built-in infrared detector which converts the radiant energy into an electrical signal which is amplified and used to control the current supply to the heating lamps 46. Inasmuch as the radiation thermometers 18 and 20 are dependent upon an accurate focus upon the object being heated the thermometers are provided with mounting means including a support rod 74 and a clamp 76 in which the rod is slidingly mounted to adjust the height of the thermometer 18 or 20. The clamp 76 is attached to a bar clamp 78 which is mounted on a horizontal support bar 80. The opposite ends of which are secured to end rod 82 which extend outwardly from a mounting plate 84. The plate 84 in turn is attached at opposite ends to the corresponding pairs of arms 48 and 50. As shown in FIG. 1 the upper end of the support rod 74 is pivoted at 86 to the underside of the thermometer 18 or 20 to enable movement of the thermometer to any angle such as indicated by the broken line positions 18a and 20 a.

The distance between each thermometer 18 and 20 and its corresponding panels 48 and 50, respectively, is maintained by a tube 88 and 90, respectively, one end of which is rigidly fixed to the optic system of the thermometer. The other end of each tube 88 and 90 is pro vided with a ball 92 and 94, respectively, which ball has a bore aligned with the interior opening of the tube for transmitting the infrared radiation reflected from the heated layer 42 of resin.

As shown more particularly in FIG. 5, the ball 94 is secured between a vertical plate 96 on the front side of the panel 16 and a mounting bracket 98 which is secured in place behind a pair of lamps 46. Thus, the combination of the ball 94 and the tube 90 maintains the required focus distance between the thermometers 18 and 20 and the inner surfaces of the corresponding panels 14 and 16. The remainder of the focus distance from the thermometers l8 and 20 to the layer 42 of resin is a measured distance 100 between the ball 94 and the particular area on the layer 42 selected for temperature measurement during the curing period.

What is claimed is:

1. An oven suitable for curing a heat-hardenable, resinous coating on coil windings in the slots of a magnetic core and for accurately and automatically controlling the temperature of said coating comprising 1. at leastone infrared heating panel directed at said coating;

2. an optical radiation thermometer which measures infrared radiation and generates an electrical signal proportional to said radiation, said electrical signal automatically controlling the output of said infrared heating panel; and

3. means for directing said thermometer at a selected point on said coating.

2. An oven according to claim 1 wherein said oven encloses said coating and said infrared heating panel on four sides and on top.

5. An oven according to Claim 1 which includes at least two opposing infrared heating panels, each heating panel and said thermometer being fixed rela- 1 tive to said ball.

directed at said coating and each containing a multiplicity of heating elements.

6. An oven according to Claim 5 wherein said panels are suspended from tracks and the distance between said panels can be altered by moving said panels along said tracks. 

1. An oven suitable for curing a heat-hardenable, resinous coating on coil windings in the slots of a magnetic core and for accurately and automatically controlling the temperature of said coating comprising
 1. at least one infrared heating panel directed at said coating;
 2. an optical radiation thermometer which measures infrared radiation and generates an electrical signal proportional to said radiation, said electrical signal automatically controlling the output of said infrared heating panel; and
 3. means for directing said thermometer at a selected point on said coating.
 2. an optical radiation thermometer which measures infrared radiation and generates an electrical signal proportional to said radiation, said electrical signal automatically controlling the output of said infrared heating panel; and
 2. An oven according to claim 1 wherein said oven encloses said coating and said infrared heating panel on four sides and on top.
 3. means for directing said thermometer at a selected point on said coating.
 3. An oven according to Claim 2 which is mounted on wheels and can be moved back and forth, said oven having at least one door on at least one side, said side being perpendicular to the direction of motion of said oven.
 4. An oven according to claim 1 wherein said means for directing said thermometer is a ball and socket joint, said socket being fixed relative to said infrared heating panel and said thermometer being fixed relative to said ball.
 5. An oven according to Claim 1 which includes at least two opposing infrared heating panels, each directed at said coating and each containing a multiplicity of heating elements.
 6. An oven according to Claim 5 wherein said panels are suspended from tracks and the distance between said panels can be altered by moving said panels along said tracks. 